Linear ultrasonic motor and lens apparatus and image pickup apparatus using the same

Abstract

A linear ultrasonic motor includes a vibrator having a piezoelectric element, a movable part applying a pressing force to the vibrator and bringing the vibrator into pressed contact with a base part, a cover part being fixed to the base part, a rolling part being rollably held between a movable guide part of the movable part and a cover guide part of the cover part, and a body to be driven having a transmission member that is pivotably supported and able to move only in the movable direction. The transmission member includes a bias part that abuts on a transmission part of the movable part and applies a biasing force of biasing the movable part to the rolling part to the transmission part. The rolling part is held by a resultant force of the pressing force or a reaction force of the pressing force, and the biasing force.

What is claimed is: 
     
       1. A driving apparatus comprising:
 a vibrator, the vibrator having a piezoelectric element; 
 a contact member, the contact member contacting the vibrator; 
 a holding part, the holding part holding the vibrator, which is applied, by an elastic member, a pressing force to press the vibrator against the contact member, wherein the contact member and the holding part are able to be relatively moved by an excitation of the piezoelectric element; 
 a first transmission member, the first transmission member being movable in association with the relative movement of the contact member and the holding part; 
 a first guide part, the first guide part being movable with the vibrator and the first transmission member relative to the contact member; 
 a rolling part being rollably held between the first guide part and a second guide part, the second guide part being movable with the contact member relative to the vibrator; and 
 a body to be driven, the body to be driven having a second transmission member that is pivotably supported and is movable with the first transmission member in a direction of the relative movement, 
 wherein, 
 the second transmission member comprises a bias part that abuts on the first transmission member and applies a biasing force of biasing the holding part to the rolling part to the first transmission member, and 
 the rolling part is held by a resultant force of the pressing force or a reaction force of the pressing force, and the biasing force. 
 
     
     
       2. The driving apparatus according to  claim 1 , wherein the rolling part and the first transmission member are arranged so as to be arrayed in a direction of the pressing force, when projected onto a plane perpendicular to a movable direction. 
     
     
       3. The driving apparatus according to  claim 1 , wherein the vibrator has a contact part, and the first transmission member is arranged so as to be arrayed or match with the contact part in a moving direction of the holding part. 
     
     
       4. The driving apparatus according to  claim 1 , wherein the first transmission member is arranged so as to be arrayed or match with the rolling part in a movable direction. 
     
     
       5. The driving apparatus according to  claim 1 , wherein the first transmission member has a convex shape, and is engaged with a concave portion provided in the second transmission member. 
     
     
       6. The driving apparatus according to  claim 1 , wherein the first transmission member has a spherical surface shape formed integrally with the holding part, and comes in point contact with the second transmission member. 
     
     
       7. The driving apparatus according to  claim 6 , wherein the first transmission member is formed from a hard ball, the hard ball being made of one of ceramic, stainless steel, brass, tungsten carbide and carbon steel. 
     
     
       8. The driving apparatus according to  claim 1 , wherein the bias part comprises a torsion spring. 
     
     
       9. The driving apparatus according to  claim 1 , wherein the rolling part is formed of a spherical rolling ball. 
     
     
       10. The driving apparatus according to  claim 1 , wherein the body to be driven comprises a lens retention frame. 
     
     
       11. A lens apparatus comprising the driving apparatus according to  claim 10 , and a guide bar, the guide bar guiding the lens retention frame. 
     
     
       12. The lens apparatus according to  claim 11 , further comprising a steady brace bar, the steady brace bar extending in the same direction as the guide bar and preventing a rotation of the lens retention frame due to the biasing force of the bias part. 
     
     
       13. An image pickup apparatus comprising the lens apparatus according to  claim 11 . 
     
     
       14. The driving apparatus according to  claim 1 , wherein the driving apparatus comprises a linear ultrasonic motor in which the piezoelectric element causes an ultrasonic vibration. 
     
     
       15. The driving apparatus according to  claim 1 , wherein the first transmission member is movable with the holding part. 
     
     
       16. The driving apparatus according to  claim 1 , wherein the first transmission member is movable with the contact member. 
     
     
       17. The driving apparatus according to  claim 1 , wherein the rolling part comprises a plurality of ball members,
 wherein the direction of the relative movement is an x axis, a direction of the pressing force of the elastic member is a z axis, and 
 wherein a contact point of the first transmission member and the second transmission member is arranged between the plurality of ball members in a y axis perpendicular to the x axis and the z axis. 
 
     
     
       18. A driving apparatus comprising:
 a vibrator having a piezoelectric element; 
 a contact member contacting the vibrator, 
 a holding part holding the vibrator and applying, by a first elastic member, a pressing force to the vibrator to press the vibrator against the contact member, so that a relative movement is caused between the contact member and the holding part when the piezoelectric element vibrates; 
 a first transmission member movable in association with the relative movement of the contact member and the holding part; 
 a first guide part which guides the relative movement between the contact member and the holding part along a first direction; 
 a rolling part being rollably held between the first guide part and a second guide part, wherein the second guide part is arranged along the first direction; and 
 a body to be driven having a second transmission member that is pivotably supported by the body and is movable, by engaging with the first transmission member, along the first direction, 
 wherein: 
 the second transmission member comprises a bias part that abuts on the first transmission member and applies a biasing force to the first transmission member with a second elastic member, and 
 the rolling part is held by the pressing force or a reaction force of the pressing force, and the biasing force. 
 
     
     
       19. The driving apparatus according to  claim 18 , wherein the rolling part and the first transmission member are aligned in a direction of the pressing force, when viewed in the first direction. 
     
     
       20. The driving apparatus according to  claim 18 , wherein the vibrator has a contact part which contacts with the contact member, and the first transmission member is aligned with the contact part in a direction of the pressing force when viewed in the first direction. 
     
     
       21. The driving apparatus according to  claim 18 , wherein the first transmission member is aligned with at least one of plural balls comprising the rolling part in a direction of the pressing force when viewed in the first direction. 
     
     
       22. The driving apparatus according to  claim 18 , wherein the first transmission member has a convex shape, and is engaged with a concave portion provided in the second transmission member. 
     
     
       23. The driving apparatus according to  claim 18 , wherein the first transmission member has a spherical surface formed integrally with the holding part, and engages with a recess of the second transmission member. 
     
     
       24. The driving apparatus according to  claim 23 , wherein the first transmission member includes a hard ball made of one of ceramic, stainless steel, brass, tungsten carbide and carbon steel. 
     
     
       25. The driving apparatus according to  claim 18 , wherein the second elastic member includes a torsion spring. 
     
     
       26. The driving apparatus according to  claim 18 , wherein the rolling part includes at least one ball. 
     
     
       27. The driving apparatus according to  claim 18 , wherein the body to be driven comprises a lens retention frame. 
     
     
       28. A lens apparatus comprising the driving apparatus according to  claim 27 , and a first guide bar for guiding the lens retention frame. 
     
     
       29. The lens apparatus according to  claim 28 , further comprising a second guide bar extending in the same direction as the first guide bar, for preventing a rotation of the lens retention frame due to the biasing force of the bias part. 
     
     
       30. An image pickup apparatus comprising the lens apparatus according to  claim 28 . 
     
     
       31. The driving apparatus according to  claim 18 , further comprising a drive circuit for driving the piezoelectric element to cause an ultrasonic vibration. 
     
     
       32. The driving apparatus according to  claim 18 , wherein the first transmission member is movable with the holding part. 
     
     
       33. The driving apparatus according to  claim 18 , wherein the first transmission member is movable with the contact member. 
     
     
       34. The driving apparatus according to  claim 18 , wherein the rolling part includes two balls which are separately arranged along the first direction,
 wherein a contact point of the first transmission member and the second transmission member is arranged between the two balls.